August 30, 2011

Poor Sleep Quality Can Affect Blood Pressure

by editor

A new study has found that older men who suffer from a lack of deep sleep are nearly twice as likely to have high blood pressure (HBP), reports BBC News.

The new research, published in Hypertension: Journal of the American Heart Association, suggests that reduced slow wave sleep (SWS) is a powerful predictor for developing the condition that causes deadly heart attack, stroke and other health problems.

SWS, a deep stage of sleep, is characterized by non-rapid eye movement (REM) from which it is difficult to awaken. It is represented by relatively slow, synchronized brain waves called delta activity on an electroencephalogram (EEG).

Researchers from the Outcomes of Sleep Disorders in Older Men Study found that people with the lowest level of SWS had an 80 percent increased risk of developing high blood pressure.

Researchers, led by Professors Susan Redline and Peter C. Farrell of Brigham and Women´s Hospital in Boston, Massachusetts, measured the sleep patterns of 784 men with average age of 75 to find how long each spent in SWS. They discovered that those who spent less than 4 percent of their sleep in SWS were 80 percent more likely to develop HBP.

The men in the study also generally suffered from shorter sleep duration, waking up more times during the night and had more severe sleep apnea.

The findings were not influenced by body weight despite many of the men being overweight or obese. Obesity is a well-recognized risk factor for high blood pressure.

“Our study shows for the first time that poor quality sleep, reflected by reduced slow wave sleep, puts individuals at significantly increased risk of developing high blood pressure, and that this effect appears to be independent of the influence of breathing pauses during sleep,” said Prof Redline.

“Although women were not included in this study, it's quite likely that those who have lower levels of slow wave sleep for any number of reasons may also have an increased risk of developing high blood pressure,” said Prof Redline.

The British Heart Foundation said it was important for everyone to prioritize sleep, reports BBC News.

The research team said that further studies were needed to determine if improving sleep could reduce the risk of HBP.

“Whilst this study does suggest a link between lack of sleep and the development of high blood pressure, it only looked at men aged over 65,” Natasha Stewart, senior cardiac nurse at the BHF, told BBC News.

“We would need to see more research in other age groups and involving women to confirm this particular association,” she said. “However, we do know more generally that sleep is essential for staying healthy. It's important we all try to make sleep a priority and get our six to eight hours of shut-eye a night.”

The participants of the study were all 65 years of age or older and 90 percent were Caucasian. All were healthy and living in one of six communities in the United States: San Diego, Calif.; Palo Alto, Calif.; Pittsburgh, Pa.; Minneapolis, Minn.; Birmingham, Ala.; and Portland, Oregon. The study was coordinated by California Pacific Medical Center.

Prof Redline also co-led a separate study, the Sleep Heart Health Study, which showed that men were likely to have less SWS than women.

In that study, researchers found that men were also at an increased risk of high blood pressure when compared to women.

The current study raises the possibility that poorer sleep in men may partly explain the male gender predisposition to high blood pressure.

SWS has been implicated in learning and memory with recent data also highlighting its importance to a variety of physiological functions, including metabolism and diabetes, and neuro-hormonal systems affecting the sympathetic nervous system that contribute to high blood pressure, researchers said.

Good quality sleep is an important part of health, said Redline. “People should recognize that sleep, diet and physical activity are critical to health, including heart health and optimal blood pressure control.”

“Although the elderly often have poor sleep, our study shows that such a finding is not benign. Poor sleep may be a powerful predictor for adverse health outcomes. Initiatives to improve sleep may provide novel approaches for reducing hypertension burden,” Redline concluded.
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